Assessing the potential cost effectiveness of pneumococcal vaccines in theUS - Methodological issues and current evidence

Pneumococcal disease imposes a notable burden on society, particularly in t he elderly and those at high risk of complications. Preventive strategies, especially vaccines, are possibly the best way to minimise such a burden. W e report on the conduct and results of a preliminary exploratory review of the economics of pneumococcal vaccines in the elderly population in the US. After extensive electronic and manual searches, we identified 5 economic e valuations that fulfilled our study criteria. From these we extracted key e conomic variables and assessed the quality of the studies against the crite ria in the checklist for authors and peer reviewers of economic submissions to the British Medical Journal. We found variation of quality of study des ign such as a lack of clarity in the treatment of indirect costs and a fail ure to present the data on resource use and costs separately. We carried ou t supplementary searches to assess the quality of the epidemiological and e fficacy evidence upon which the economic models were based and found contra dictory evidence of effects of the vaccines, which included the results of 2 meta-analyses. One of these meta-analyses reported that retrospective stu dies, especially case-control studies, tended to underestimate the protecti ve efficacy of the vaccine by as much as 20%. We believe that a well resour ced Cochrane review of the clinical evidence of the effects of the vaccines should be carried out before any further economic studies. No more economi c modelling should take place before such a review is undertaken.